 
 (defn set-default-track
   "Sets the default video, audio or subtitle track."
-  [file track]
+  [file track & [info]]
   (when (and (= (file-type file) :mkv) @mkvpropedit)
-    (let [info (video-info (io/file file))
+    (let [info (or info (video-info (io/file file)))
           streams (:streams info)
           default (container-track info track)
           codec (:codec_type default)

      (if (zero? (:exit exec))
        (do
          (log/info "encoding was successful")
          (clear-subtitles (:output spec))
          (clean spec)
          spec)
        (do

          (when-not (zero? (:exit exec))
            (log/warn "changing default track failed:" \newline cmd \newline exec)))))))

(defn set-default-audio-track
  "Ensures only one track is set as the default audio track."
  [file]
  (let [info (video-info (io/file file))
        track (-> info audio-streams default-audio :index)]
    (set-default-track file track info)))

(def mkclean (delay (exec? "mkclean")))

(defn clean
